Power transmission

ABSTRACT

A plurality of pressure energy-translating devices each of which is comprised of a variable hydraulic pump driving a hydraulic motor, the outputs of which are connected to a common workload to be driven by the same; and, means for controlling the pressure output of the pumps whereby the driving motors each assume half of the common workload.

Unite States Patent Inventor Harry J. Nowicki [56] References Cited 24 5UNITED STATES PATENTS P N9 5 1,900,050 3/1933 Ernst 60/97EUX Filed Nov.14, 1968 Patented A r 27 1971 2,400,685 5/1946 Collins 60/97 E Assi e6lhmd corporafion 2,580,946 1/1952 Orshansky eta]. 60/97EUX Tmwvlich3,443,379 5/1969 Weisenbach 60/97EUX Primary Examiner-Edgar W. GeogheganAttorney-Van Meter and George POWER TRANSMISSION 6 Claims, 1 DrawingFig. I U.S.Cl 60/52, CT: A plurality of pressure energy-translating60/97, 74/661 devices each of which is comprised of a variable hydrauliclnt.Cl ..Fl5b 15/18, pump driving a hydraulic motor, the outputs ofwhich are F 15b 18/00, FOlb 21/00 connected to a common workload to bedriven by the same; Field of Search 60/97 (E), and, means forcontrolling the pressure output of the pumps 52 (VSP), 53 (W & R);91/412; 103/1 1 (A); whereby the driving motors each assume half of thecommon 74/661 workload.

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28 e 60 ,64 A .L l I 32 22 I PATENTED APRZ'I IBYI JNVHNTOR. HARRY J.NOW/CK! ATTORNEYS rowan TRANSMISSION BACKGROUND OF THE INVENTION Thisinvention relates to power transmissions and is particularly applicableto those of the type comprising two or more fluid pressureenergy-translating devices, one of which may function as a pump, and theother as a fluid motor. More particularly, this invention relates to animprovement in a system employing a plurality of power transmissions inwhich the mechanical output of each transmission is connected to acommon workload.

Generally, when a single load is to be driven, only one pump/motorcombination of suitable size is required; however, there are certainapplications in which the distribution of the weight of such a systemfor the purpose of balance necessitates the use of a plurality ofpump/motor combinations whose total output would equal that of thesingle combination, but which achieves the desired distribution ofweight.

Such a system would comprise, for example, a pair of pump/motorcombinations in which the pumps are of the variable displacement typewhile the motors are of the fixed displacement type. The mechanicaloutputs of the motors are connected to a common workload andtheoretically each motor should assume half the load requirements.However, it has been found that one of the driving motors assumessubstantially all of the load while the other motor acts as a follower.Such a condition is both uneconomical, which results in a reduction inthe life of the unit assuming the greater portion of the workload.

It would thus be very desirable to synchronize the outputs of the twomotors used in the one driving operation so as to assure that each motorassumes approximately one-half the workload.

SUMMARY OF THE INVENTION This invention comprises two pressureenergy-translating devices, each having a variable displacement fluidpump driving a fluid motor, the outputs of which are driving a commonworkload; an actuator means which senses the operation pressures of bothdevices; and, means which vary the output pressure of one of saidvariable pumps in response to said sensing means for maintaining theoperating pressures of both devices at an approximately equal value.

It is therefore an object of this invention to provide a powertransmission system employing a plurality of fluid pumps and motors inwhich the mechanical outputs are connected to a common load and in whicheach of said motors shares an equal portion of the workload.

It is also an object of this invention to provide such a system which isof low cost, efficient, and which has a long life.

Further objects and advantages of the present invention will becomeapparent from the following description, reference being made therein tothe accompanying drawing wherein a preferred form of the presentinvention is clearly shown.

IN THE DRAWING The single FIGS. is a diagrammatic illustration of afluid pressure energy transmission system incorporating a preferred formof the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing,there is shown a presently preferred, but merely illustrative embodimentof the inventive principles: a power transmission circuit indicated bythe numeral 10. It will be understood that the hydraulic circuitdescribed herein and forming a part of the present invention may beconnected to a hydraulic pump or motor or hydraulic operating unit ofany type or design, asthe present invention has to do with thecirculating system rather than the means to be operated.

ineflicient and The driving system is shown in the single figure asconsisting of a leading or master section A and a follower-section B todrive, respectively, gears 12 and I4 which are connected to a commonworkload, not shown, by means of gear 16 and shaft 18.

The master section A comprises a variable displacement pump 20 connectedin a closed circuit by conduits 22 and 24 to a fluid motor 26. The pump20 may be of any of the wellknown types of variable displacement unitsand, in the present embodiment, it is illustrated as being manuallyoperable by means of a handle 28. The motor 26 may also be of any of thewell-known types of hydraulic motors as is driven in the conventionalmanner by means of high-pressure fluid admitted from pump 20 through theconduit 22. Fluid is returned to the pump from the motor by means ofconduit 24.

Any suitable prime mover, such as an electric motor as illustrated at30, is mechanically connected through suitable means to an input shaft32 of the pump for driving the same.

The follower section B is substantially the same as the master section Aand comprises a variable displacement pump 34 connected in a closedcircuit by conduits 36 and 38 to a fluid motor 40. The pump may also beof any of the wellknown types of variable displacement units and in thepresent embodiment, it is varied by means of stroking arm 42 whichextends from a pressure synchronizing linear actuator 44. Pressure fluidis supplied to and from motor 40 by means of pump 34 in a manner similarto the motor 26 within the master section A; that is, high-pressurefluid is supplied to the motor by means of conduit 36 and is returned tothe pump by means of conduit 38.

In the present embodiment, if the stroking arm 42 is shifted upwardly,as viewed in the F IG., the displacement of pump 34 will be increasedand thus, the amount of fluid pressure being directed to the motor 40will also increase. In a similar manner, if the stroking arm 42 isshifted downwardly, as viewed in the F IG., the displacement of pump 34and the fluid pressure being directed to the motor 40 will decrease.

A suitable prime mover such as an electric motor is also provided in thefollower section B at 46 and is mechanically connected through asuitable means to an input shaft 48 of the pump 34 for driving the same.

The pressure synchronizing actuator 44 is of the doubleacting,nondifferential type and comprises a housing 50 having a bore 52 thereinin which is reciprocally mounted a piston 54 forming pressure chambers56 and 58 on opposite sides thereof. The piston 54 is connected to thestroking arm 42 of pump 34 for driving the same and is connected to asecond piston arm 60 on the opposite face thereof and extends from thepiston to a point which is external of the housing 50. This isprovidedfor the purpose of having the opposite faces of piston 54, which areexposed to the pressure chambers 56 and S8, of an equal area. It canthus be seen that the piston 54 and thus the stroking arm 42 can beactuated only if a differential in pressures exists across the opposingpressure chambers 56 and 58.

The pressure chambers 56 and 58 are respectively directly connected tothe pump high-pressure conduits 36 and 22 by means of conduits 62 and 64for the purpose of supplying respectively the output pressures of pumps34 and 20 to the same.

In operation, both electric motors are actuated to supply the motivepower necessary to drive the pumps, which in turn supply pressure fluidto their associated motors. The motors being coupled to a commonworkload will both be operated at the same speed. At the same time,pressure fluid from both of the pumps high-pressure conduits 36 and 22is respectively supplied directly to the pressure chambers 56 and 58 ofactuator 44 and respectively act against the opposite faces of piston54. In the event the pressure in the follower section B effect thatpiston 54 will be shifted upwardly stroking the pump 34 to a greaterdisplacement. This will cause the pressure in the pump outlet conduit 36to increase until it equals the pressure in the master section A conduit22 which had been decreasing as motor 40 assumed an increasing portionof the load. When the pressures in both conduits 22 and 36 are equal,the actuator 44 will reach a stabilized position with the net effectthat both motors are now sharing approximately half of the commonworkload.

it can thus be seen that the present invention has provided a powertransmission system employing a plurality of fluid pumps and motors inwhich the mechanical output of the motors drives a common workload whilesharing an equal portion of that load; and one which is of low cost,efficient, simple in operation, and of a long life.

While the form of embodiment of the present invention as hereindisclosed constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claimswhich follow.

lclaim:

l. A pressure energy-translating system for driving a machinecomprising:

a plurality of power transmissions, each having a variable displacementfluid pump driving a fluid motor said motor generating a mechanicaloutput in response to the operating pressure of said pump;

means connecting said mechanical outputs to said machine forsimultaneous driving of the same;

actuator means directly actuated by the difference between the operatingpressures of said fluid pumps for controlling the displacement of one ofsaid pumps to increase or decrease the operating pressure of said onepump to a value equal to the operating pressure of the other of saidpumps, whereby the mechanical output of each motor is of the samemagnitude.

2. A pressure energy translating system as described in claim 1 whereinsaid one pump is connected to one of said fluid motors in a closedcircuit including a first high-pressure conduit so that the pumpdelivers high-pressure fluid to drive the said one fluid motor; whereinsaid other pump is connected to the other of said fluid motors in aclosed circuit including a second high-pressure conduit so that saidother pump delivers high-pressure fluid to drive said other fluid motor;wherein said actuator means comprises an enclosed housing having a borewith a pressure-responsive piston reciprocally mounted therein forming apair of pressure chambers on opposite sides thereof, one of which isdirectly connected to said first high-pressure conduit, the otherdirectly connected to said second high-pressure conduit; and means forvarying the displacement of said one pump in response to the position ofsaid piston.

3. A pressure energy-translating system as described in claim 2 whereinsaid displacement varying means is connected to one side of said piston.

4. A pressure energy-translating system as described in claim 3 whereinsaid opposite sides of said piston have pressure-responsive areas,exposed to their corresponding pressure chambers, which are of an equalmagnitude whereby an increase in said second high-pressure conduit willcreate a pressure differential across said piston to shift the positionof the same for varying the displacement of said one pump.

5. A pressure energy translating system as described in claim 4 whereinsaid increase in said second high-pressure conduit results in anincrease of the displacement of said one pump.

6. A pressure energy-translating system as described in claim 5 whereinthe displacement of said other pump is manually operated.

1. A pressure energy-translating system for driving a machinecomprising: a plurality of power transmissions, each having a variabledisplacement fluid pump driving a fluid motor said motor generating amechanical output in response to the operating pressure of said pump;means connecting said mechanical outputs to said machine forsimultaneous driving of the same; actuator means directly actuated bythe difference between the operating pressures of said fluid pumps forcontrolling the displacement of one of said pumps to increase ordecrease the operating pressure of said one pump to a value equal to theoperating pressure of the other of said pumps, whereby the mechanicaloutput of each motor is of the same magnitude.
 2. A pressure energytranslating system as described in claim 1 wherein said one pump isconnected to one of said fluid motors in a closed circuit including afirst high-pressure conduit so that the pump delivers high-pressurefluid to drive the said one fluid motor; wherein said other pump isconnected to the other of said fluid motors in a closed circuitincluding a second high-pressure conduit so that said other pumpdelivers high-pressure fluid to drive said other fluid motor; whereinsaid actuator means comprises an enclosed housing having a bore with apressure-responsive piston reciprocally mounted therein forming a pairof pressure chambers on opposite sides thereof, one of which is directlyconnected to said first high-pressure conduit, the other directlyconnected to said second high-pressure conduit; and means for varyingthe displacement of said one pump in response to the position of saidpiston.
 3. A pressure energy-translating system as described in claim 2wherein said displacement varying means is connected to one side of saidpiston.
 4. A pressure energy-translating system as described in claim 3wherein said opposite sides of said piston have pressure-responsiveareas, exposed to their corresponding pressure chambers, which are of anequal magnitude whereby an increase in said second high-pressure conduitwill create a pressure differential across said piston to shift theposition of the same for varying the displacement of said one pump.
 5. Apressure energy translating system as described in claim 4 wherein saidincrease in said Second high-pressure conduit results in an increase ofthe displacement of said one pump.
 6. A pressure energy-translatingsystem as described in claim 5 wherein the displacement of said otherpump is manually operated.